copeland



UNITED STATES PATENT UFFTGE.

CHAS. W. COPELAND, OF NEW YORK, N. Y.

VALVE AND EXHAUST-PASSAGE 0F STEAM-ENGINES.

Specification of Letters Patent No. 14,225, dated. February 12, 1856.

To all whom it may concern:

Be it known that I, CHAS. IV. COPELAND, of the city, county, and State of New York, mechanical engineer, have invented a new and useful Impovement in the Valves of Steam-Engines, and that the following specification, taken in connection with the drawings, is a full, clear, and exact description thereof.

In the drawings Figure 1 is a plan of the bottom of a long or double side valve made according to my invention. Fig. 2 is a plan of the seat to which such a valve is applicable showing also the cylinder Fig. 3 is a longitudinal section through the same valve, seat, ports, steam passages and cylinder and Figs. 4, 5 and 6 are corresponding plans and section of a short slide valve and seat and through both made also according to my invention.

The same letters refer to the same parts in all the figures.

It is a fact well known to those conversant with steam engines that the exhaust or escape side pipes passages and valves should be larger in area than those which serve for the admission of steam into the cylinder; for a large enough passage for steam having considerable pressure is not suflicient to pass the same steam in the same time when reduced to or below the pressure of the atmosphere and consequently much increased in bulk or volume any throttling of the escape passages materially diminishes the effective power of either condensing or non-condensing engines. As the pressure in the exhaust side of the cylinder which resists the power of the steam coming from the boiler and driving the piston, is increased thereby and the steam on the exhaust side is of greater tension than that in the condenser in the one case or than the atmosphere itself in the other.

In engines using puppet qr crown or other valves of the lifting variety and having distinct passages for escape and entering steam or in those using two sets of slide valves, with two or more sets of stems, one for exhaust and the other for steam this difficulty can and has been met and remedied by mere enlargement of the exhaust valves and passages. There is however a large class of engines in which slide valves acted upon by the same stem and serving both for entrance "and exhaust are still employed. These valves are known as long and short slide D and piston valves and by other names but all have the same peculiarity in that they open a passage by sliding over a seat instead of by lifting or rising from it and'to all such valves my invention is appllcable when all the passages for steam and exhaust are opened and closed by valves whose motion is coincident.

The object of my invention is in such valves to secure a larger passage for exhaust than for steam, without complicating the valve gear and the nature of my inventlon consists in so constructing the valve and seat that the former shall in its operation open two or more passages for the exhaust instead of one as is now the case substantially in the manner and for the purposes herein set forth.

In order to exemplify my invention clearly, I have in the drawings shown it as applied both to a short and a long slide valve.

By reference to Figs. 1 and 2 it will be seen that the usual cup 00 of the valve through which the exhaust steam passes is traversed by a bar a whose surface nearest the valve seat is level with the face of the valve while it extends backward into the cup only a short distance leaving a free passage for steam between it and the bottom of the cup.

Each valve seat instead of having two apertures as usual one connecting with the cylinder and the other with the exhaust passage f has three openings one of which I) leads to the exhaust passage while both the others 0 and (Z lead to the cylinder.

The bars above referred to are so situated and are of such length, that they always cover the passages in the middle of the seat while steam from the boiler is passing into the cylinder through the passage nearest the ends of the cylinder but when steam is escaping through the end passage or port into the cup then the bar uncovers the middle passage and steam can escape through it also, into the same cup and thence through the usual large aperture Z) into the exhaust passage f.

In Fig. 3 the valve is shown in two positions red shading marking the one and black shading the otherwhen it occupies the latter position the passages leading into the cylinder are all closed and no steam is either entering or leaving it.

When the valve occupies the position shown by the red shading, steam is entering the left end of the cylinder (see arrow) by the end passage while the center passage is closed by the bar thus preventing blowing through into the exhaust passage, while at the other end of the cylinder all three passages are open into the cup so that exhaust steam passes freely through c and (Z into the cup and thence through Z) into the exhaust passage.

Mere inspection will show that the exhaust apertures into the cup are collectively of much greater area than the single passage through which steam enters. When the engine takes steam on the right valve is reversed over to the left and the parts occupy the same relative position that the red lines point out, except that the exhaust and steam have changed sides so that the piston will move in the opposite direction.

A short slide valve may be considered as a long slide shoved together so that the two cups form one while the seat is at the same time shortened up so that the two apertures leading to the exhaust passage also unite in one. This consideration obviates the necessity of further description of Figs. 4 and 6 as the seats bars passages etc., are altered from an ordinary single slide valve just as Figs. 1, 2 and 3 represent them as differing from an ordinary double slide. The red shadings of the valve in the sectional drawing Fig. 6, show the valve as giving steam to the left end of the cylinder while the exhaust is escaping from the right end through two passages. The black shadings represent the valve as covering all the ports or passages leading into the cylinder so that steam is neither entering nor escaping.

It is clear in both the single and double valve that the area for the passage of exhaust steam is much enlarged in comparison with that serving for its entrance and it may be still further enlarged by adding more bars and more passages or ports. It is also evident that the same additional exhaust ports and bars may be applied to double and single piston, D, and other varieties of slide valves, by any competent engineer who has been instructed by this my specification and I contemplate such application as of my invention stating this, for the reason that the usual length of a specification will. not admit of a precise description of the application of my invention to all the various forms of valves and deeming that there is already in the present description a sutlicient guide for a general application of my invention.

I claim as my own invention and desire to secure by Letters 1atent The herein described manner of increasing the area of the passages for escape steam by means of bars or their equivalents making part of the valve acting in conjunction with additional apertures or ports in the seat substantially in the way and for the purposes herein set forth.

CHAS. W. COPELAND.

Witnesses:

WM. HENRY VALLAGE, EDWARD GIFFORD. 

